It is well known to provide an electric vehicle that is powered by one or more electric motors to move the vehicle from place to place. In many instances, single electric drive motors are utilized to provide primary power which is delivered to the driven wheels by a series of mechanical devices including transmissions, differentials, drive shafts, and other components that have been employed since the automobile was introduced. In recent years, as the electric vehicle has become more commonplace, various drive system designs have been introduced as alternative methods of power delivery. However, such drive systems have inefficiencies, are complex, and traditionally do not account for environmental conditions while selectively controlling in real time each drive wheel.
An all-wheel-drive vehicle that includes a drive motor assembly at each wheel is a simple machine that has characteristics similar to any machine that is used to impart motion to a load or various loads. In the case of a vehicle, the load is only the vehicle itself as well as any additional weight of passenger(s) and any other items on board. Calculating the force required to move its mass at a given speed is a matter of applying the equation F=ma. While in the case of the conveyor, the mass being moved may be variable (given that the quantity of loads can vary) but the pathway is fixed. The combination of a fixed pathway and sensing devices defining parts of the pathway that represent various angles of load incline or decline make the vector part of the equation relatively easy to recognize. These angles are pre-defined and programmed into a “chain pull calculation”.
In the case of the vehicle, the weight or mass is generally fixed during operation (once the weight of the additional passengers and carry-ons is determined), but the acceleration and speed and vector can be randomly variable depending on the pathway the driver takes. In essence, the same classic formula describing Newton's Second Law of Motion (F=ma) is applicable to both situations. The significant difference is that in the case of the conveyor, the mass can change constantly, and in the case of the vehicle, the acceleration and speed may be changed constantly. However, in both cases, the power needed to drive the machine is predictable and can be calculated. Thus, if a mathematical model of a machine's work requirement can be built, then the power needed to move the machine can be both predicted and applied with the use of the elements described herein.
The control method and architecture described herein is an improvement over currently available approaches to power application for electric vehicles. It provides a universally applicable method that will improve performance, efficiency, and stability in various forms of vehicle systems as well as other machinery whose purpose is to move material through a manufacturing facility or on the planet's surface. The problem however is that traditional vehicle drive systems do not compensate well under all terrain conditions for the changes in torque demand as the vehicle advances along the surface of the planet or in the manufacturing environment.
In the case of AWD electric vehicles, a novel approach to power application has been developed. A primary sensing device constantly measures the physical attitude of the vehicle (primary vector data) with a gyroscope or similar instrument. One or more gyroscopes may be used as sensing devices to determine the vector attitude of the vehicle along with the speed input requirement where appropriate to calculate the overall torque demand required to move the vehicle at the speed desired. In addition, as the vehicle moves through roadway inclines and declines, the center of gravity of the vehicle will shift about the vehicle in a manner that is able to be detected by the gyroscope and calculated then utilized to apply varying torque outputs to each wheel as needed. This is similar to the effect on torque requirements of each drive on a conveyor as loads pass from one drive purview to the next causing the relative torque demand among all drives to change substantially. The present invention overcomes both of these circumstances by delivering power as required based on accurate calculations of the torque needed while instantaneously adjusting for the same in real-time.
It would be desirable to provide an intelligent drive control system that improves upon the current method of overcoming the aforementioned problems. The preferred system should be dynamic and operable to constantly change performance output of every motor within the system, in view of the constantly changing loads on the system. It would also be desirable to provide a drive control system that improves the available technology such that torque demands on the drive system are anticipated and proactively met, speed requirements are maintained, and dynamic environmental conditions are taken into consideration.
It would also be desirable to provide an improved drive control system for a multi-drive system or AWD system that continuously senses the total mass of the vehicle and is able to determine the center of gravity of the vehicle as it travels over various terrain configurations. This information is continuously delivered to an on-board microprocessor, which in turn calculates optimal torque requirements for each wheel drive mechanism of the vehicle and then sends a corresponding signal back to a drive controller for producing the optimal torque output for each drive employed with the vehicle.
It would also be desirable to provide an improved drive control system that improves delivery of balanced power and speed control to a multi-drive vehicle system and an all-wheel-drive (AWD) electric vehicle. A mathematical model allows the control system to calculate and provide required total power delivery as well as balanced power delivery to each drive within the machine system such that each motor delivers its proportional share of the power needed. Due to the nature of many machine designs, including electric vehicles, it is common to expect that if a number of motors are utilized to share the total work load, there will be times when the work load will be unevenly distributed among drive motors. The present invention overcomes the problem that this uneven power demand imposes.
One aspect of the present drive control system is that it allows for the elimination of certain commonly used major mechanical components including transmissions, differentials, torque converters, drive shafts, and other ancillary coupling components saving related costs.
Another aspect of the present invention provides a drive control system for a vehicle comprising one or more variable speed and variable torque motors for driving a vehicle. A dynamic force vector calculation program is operable to continuously calculate the torque requirements for each motor in the system. One or more sensors are employed that are operable to create a signal indicative of load conditions and, if required, additional data including the weight of such load or loads, slippage of the wheels, and terrain characteristics, and then send data to a computer. The computer is operable to process the signals from the sensors using the dynamic force vector calculation program and in turn generates real time drive torque data for each motor. A variable drive controller is operable to control each variable speed motor within the system so that proper torque is generated by each motor as is required for optimum performance. The resulting intelligent drive control system is dynamic and continuously monitors torque requirements for each motor within the vehicle system given current load data and environmental conditions so as to maximize operating efficiency of the vehicle.
Further areas of applicability of the present invention will become apparent from the detailed description provided herein. It should be understood that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are intended for purposes of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. It will be appreciated that the present invention can be utilized in a variety of vehicle drive systems, and where it is desirable to efficiently transport people and materials in a variety of terrain conditions.